Automated detection of an active audio output

ABSTRACT

An active audio output detection system and method that automatically determines the type of audio output being used on an audio playback device. Embodiments of the system and method include playing back audio content on the audio playback device (such as a mobile phone) and capturing sound during playback using an audio capture device (such as a microphone). The captured sound is analyzed to determine whether the audio playing back on the audio playback device is contained therein. If the captured sound matches the audio playing back on the audio playback device, then the active audio output is a loudspeaker. On the other hand, if the captured sound does not match the audio playing back on the audio playback device, then the active audio output is headphones.

BACKGROUND

There are several circumstances when it is advantageous to know whichaudio output on a device is active. For example, it may be desirable toknow whether audio content is being played back or reproduced on anaudio playback device (such as a mobile phone) through loudspeakers orheadphones. One situation in which this is useful is when audioprocessing is being applied to the audio signal containing the contentbeing played back. Audio signal processing typically is used to achievethe best sound possible from a playback device. Just as photography andvideo processing commonly is used to improve the visual experience of aphotograph or video, audio signal processing is frequently used toimprove the auditory experience of audio content.

The type of audio signal processing used, however, often is differentfor an audio signal played back through headphones as compared to beingplayed back over speakers. For example, audio spatial virtualization,which gives the illusion that sounds are originating from specificlocations in 3D space, is different depending on whether the audiocontent is being heard through speakers or headphones. This differencebetween audio processing techniques used can become problematic when aplayback device (such as a mobile phone) is capable of playing backaudio content either through speakers or headphones.

The playback device typically communicates with the headphones orspeakers using certain output endpoints such as lineout, Bluetooth® (aregistered trademark of Bluetooth SIG), and Wi-Fi® (a registeredtrademark of the Wi-Fi Alliance). However, in order to match the correctprocessing to the output types a listener is burdened with manuallyinforming the playback device to use headphone mode or speaker mode. Theburden on the listener can be a barrier to adoption of otherwiseattractive audio processing technologies as the listener may find iteasier to turn off the processing rather than have to manually switchbetween headphone mode and speaker mode.

Several different techniques exist to automatically identify whetheraudio content is being played back through speakers or headphones. Onesuch method is “jack detection” that detects when headphones are pluggedinto the headphone jack on the playback device. One problem, however, isthat speakers may also be plugged into the headphone jack and the jackdetection technique cannot differentiate between headphones andspeakers. Thus, the jack detection technique is not always a reliableindicator of whether headphones or speakers are in use.

Impedance matching techniques can be used to detect whether headphonesor speakers are connected to the playback device. However, impedancematching techniques often have implementation issues. Moreover,impedance matching is dependent on manufacturers to provide impedancevalues to create and maintain a database for the impedance matchingtechnique to use.

Similar to impedance matching techniques are wireless deviceidentification techniques. As noted above, Bluetooth and Wi-Fi arepopular wireless protocols that support both wireless speakers andheadphones. The wireless device identification techniques use a “deviceID” assigned to a particular wireless device to determine whether thewireless device is headphones or speakers. One problem with the wirelessdevice identification techniques is that they require the creation andmaintenance of a device database to categorize wireless devices.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

Embodiments of the active audio output detection system and methoddetermine the audio output being used on an audio playback device.Embodiments of the system and method are useful to determine, forexample, whether audio content is being played back on the audioplayback device through a loudspeaker or through headphones. This isimportant in situations where it is desirable to know whether to useaudio processing techniques optimized for loudspeakers or thosetechniques optimized for headphones. Embodiments of the system andmethod require no lookup tables or databases in order to determine thetype of audio reproduction device (such as loudspeakers or headphones)being used.

Embodiments include a method for automatically detecting an active audiooutput of an audio playback device. The method includes playing backaudio content on the audio playback device and capturing sound duringplayback using an audio capture device. The audio capture device is incommunication with the audio playback device. The method then analyzeswhether the captured sound matches the audio playing back on the audioplayback device. The method uses this analysis to determine the activeaudio output of the audio playback device. For example, if the capturedsound matches the audio playing back on the audio playback device, thenthe active audio output is a loudspeaker. On the other hand, if thecaptured sound does not match the audio playing back on the audioplayback device, then the active audio output is headphones.

The method also modifies the audio content playback based on thedetermination of the active audio output. In some embodiments the audiocapture device is a microphone on the audio playback device. In otherembodiments the audio capture device is a microphone that is incommunication with the audio playback device but not necessarily on theaudio playback device. In some embodiments the method determines theactive audio output of the audio playback device based on the analysiswithout the use of special audio tones or audio watermarks. In otherembodiments the method sends a signal from the audio playback device toanother device in communication with the audio playback deviceindicating the active audio output of the audio playback device.

Embodiments also include a method for determining a type of audioreproduction device in communication with an audio playback device. Themethod includes playing back audio content on the audio playback deviceover the audio reproduction device and listening for the audio contentduring playback using an audio capture device to determine whether theaudio content being played back is present. The method determines thatthe type of audio reproduction device is a loudspeaker if the audiocontent is present. On the other hand, the method determines that thetype of audio reproduction device is headphones if the audio content isnot present.

In some embodiments the method applies an audio processing techniquedesigned for loudspeakers if the determination is that the type of audioreproduction device is a loudspeaker. In other embodiments the methodapplies an audio processing technique designed for headphones if the ifthe determination is that the type of audio reproduction device isheadphones.

Embodiments also include a system for automatically determining a typeof audio reproduction device connected to a mobile phone. The systemincludes audio content that is played back on the mobile phone throughthe audio reproduction device. The system further includes an audiocapture device that captures sound while the audio content is beingplayed back. In addition, the system includes an analysis processor thatperforms an analysis as to whether the audio content is present in thecaptured sound and a selection processor that determines the type ofaudio reproduction device based on the analysis. In some embodiments thesystem includes an audio processing technique for loudspeakers that isapplied to the audio content if the selection processor determines thatthe type of audio reproduction device is a loudspeaker. In otherembodiments the system includes an audio processing technique forheadphones that is applied to the audio content if the selectionprocessor determines that the type of audio reproduction device isheadphones.

It should be noted that alternative embodiments are possible, and stepsand elements discussed herein may be changed, added, or eliminated,depending on the particular embodiment. These alternative embodimentsinclude alternative steps and alternative elements that may be used, andstructural changes that may be made, without departing from the scope ofthe invention.

DRAWINGS DESCRIPTION

Referring now to the drawings in which like reference numbers representcorresponding parts throughout:

FIG. 1 is a block diagram illustrating a general overview of embodimentsof an active audio output detection system and method.

FIG. 2 is a block diagram illustrating a general overview of oneembodiment of the active audio output detection system and method.

FIG. 3 is a flow diagram illustrating embodiments of the operation ofthe active audio output detection system and method shown in FIGS. 1 and2.

FIG. 4 is a block diagram illustrating the embodiments of the activeaudio output detection system and method shown in FIG. 2 where theactive audio output is a loudspeaker.

FIG. 5 is a block diagram illustrating the embodiments of the activeaudio output detection system and method shown in FIG. 2 where theactive audio output is headphones.

FIG. 6 is a flow diagram illustrating alternate embodiments of theoperation of the active audio output detection system and method shownin FIGS. 1-5.

DETAILED DESCRIPTION

In the following description of embodiments of an active audio outputdetection system and method reference is made to the accompanyingdrawings. These drawings shown by way of illustration specific examplesof how embodiments of the active audio output detection system andmethod may be practiced. It is understood that other embodiments may beutilized and structural changes may be made without departing from thescope of the claimed subject matter.

I. System Overview

Embodiments of the active audio output detection system and method areused to automatically detect which audio output of a device is active.This is achieved by listening during audio playback of audio content onthe device to determine whether the audio content being played back canbe heard. If so, then the active audio output is loudspeakers.Otherwise, the active audio output is headphones. An overview ofembodiments of the codec and method will now be discussed.

FIG. 1 is a block diagram illustrating a general overview of embodimentsof an active audio output detection system 100 and method. Referring toFIG. 1, the active audio output detection system 100 includes an audioplayback device 105 (such as a mobile phone). The audio playback device105 includes a playback processor 110, an analysis processor 115, and aselection processor 120. The playback processor 110 plays back audiocontent 125 on the audio playback device 105 through an audio output130. The audio output 130 may have one or more connected audioreproduction devices, such as loudspeakers and headphones.

The analysis processor 115 takes input from an audio capture device(such as a microphone) and the playback processor 110 and performs ananalysis on the two inputs. As explained in detail below, the analysisis to determine whether the audio content 125 playing back on the audioplayback device 105 is present in the sounds being capture by the audiocapture device 135 during the same time period. In alternate embodimentsthe analysis is to determine whether an audio indicator (such as aspecial audio tone or an audio watermark) is present in the capturedsounds.

The selection processor 120 interprets the analysis done by the analysisprocessor 115 and determines the type of active audio output. In someembodiments the type of active audio output is either loudspeakers orheadphones. In some embodiments the audio playback device 105 includesoptional (as shown by the dashed lines in FIG. 1) post-processingtechniques, such as post-processing technique #1 140 and post-processingtechnique #2 150. In some embodiments the two post-processing techniquesare one for loudspeakers and one for headphones. The term “headphones”includes traditional headphones, earbuds, earphones, and otherdirect-to-ear or near-the-ear audio rendering devices.

In some embodiments of the active audio output detection system 100 andmethod the audio capture device 135 is contained on the audio playbackdevice 105. In other embodiments the audio capture device 135 is incommunication with but not contained on the audio playback device 105.

FIG. 2 is a block diagram illustrating a general overview of oneembodiment of the active audio output detection system 100 and method.Referring to FIG. 2, illustrated is the embodiments where the activeaudio output detection system 100 is implemented on a mobile phone 200.The mobile phone 200 contains the playback processor 110, the analysisprocessor 115, and the selection processor 120, as described above. Themobile phone also includes microphone 210 and the audio output 130includes a loudspeaker 220 and a headphone jack 230. This embodimentincludes an audio post-processing technique for loudspeakers 240 and anaudio processing technique for headphones 250.

II. Operational Details

The details of the active audio output detection system 100 and methodwill now be discussed. It should be noted that many variations arepossible and that one of ordinary skill in the art will see many otherways in which the same outcome can be achieved based on the disclosureherein.

FIG. 3 is a flow diagram illustrating embodiments of the operation ofthe active audio output detection system 100 and method shown in FIGS. 1and 2. Referring to FIG. 3, the operation begins by playing back audiocontent on an audio playback device (box 300). During audio playbacksound is captured (box 310). The method performs an analysis between thecaptured sound and the audio content being played back (box 320). Thisanalysis determines whether the audio content being played is present inthe captured sound.

The method determines the active audio output based on the analysis (box330). In some embodiments, if the audio content being played is presentin the captured sound then the active audio output is a loudspeaker. Onthe other hand, if the audio content is not present then the activeaudio output is headphones.

The method then modifies the audio content playback based on thedetermination (box 340). In some embodiments an audio processingtechnique for loudspeakers is applied if the determination is that theactive audio output is headphones. If determination is that the activeaudio output is loudspeakers, then an audio processing technique forloudspeakers is applied. In some embodiments the system 100 sends asignal from the audio playback device 105 to another device incommunication with the audio playback device 105. This signal indicatesand notifies the other device as to which is the active audio output ofthe audio playback device.

FIG. 4 is a block diagram illustrating the embodiments of the activeaudio output detection system 100 and method shown in FIG. 2 where theactive audio output is a loudspeaker. Referring to FIG. 4, the playbackprocessor 120 is playing back the audio content 125 through theloudspeaker 220. At the same time as the playback of the audio content125 the microphone is listening and captures sound 400 from theloudspeaker 220. The microphone sends the captured sound to the analysisprocessor 115 that compares the captured sound to the audio contentbeing played back. The analysis processor determines that the audiocontent is present in the captured sound. The selection processor 120receives this analysis and determines that the active audio output isthe loudspeaker 220. The system 100 modifies the audio content playbackto apply the audio processing technique for loudspeakers 240 to theoutput signal containing the audio content. Note that in FIG. 4 theaudio processing technique for headphones 250 is shown as a dashed boxto indicate that this processing technique is not active because theactive audio output is the loudspeaker 220.

FIG. 5 is a block diagram illustrating the embodiments of the activeaudio output detection system 100 and method shown in FIG. 2 where theactive audio output is headphones. Referring to FIG. 5, the playbackprocessor 120 is playing back the audio content 125 through theheadphones 500. The sound 510 containing the audio content 125 beingplayed back is only coming through the headphones and cannot be heardexcept by the listener (not shown) wearing the headphones 500. At thesame time as the playback of the audio content 125 the microphone islistening but does not capture the sound 510 containing the audiocontent 125 coming through the headphones 500. The microphone sends thecaptured sound to the analysis processor 115 that compares the capturedsound to the audio content being played back. The analysis processordetermines that the audio content is not present in the captured sound.The selection processor 120 receives this analysis and determines fromthis analysis that the active audio output is the headphones 500. Thesystem 100 modifies the audio content playback to apply the audioprocessing technique for headphones 250 to the output signal containingthe audio content. Note that in FIG. 5 the audio processing techniquefor loudspeakers 240 is shown as a dashed box to indicate that thisprocessing technique is not active because the active audio output isthe headphones 500.

III. Alternate Embodiments and Exemplary Operating Environment

Alternate embodiments of the active audio output detection system 100and method are possible. By way of example, FIG. 6 is a flow diagramillustrating alternate embodiments of the operation of the active audiooutput detection system 100 and method shown in FIGS. 1-5. The methodbegins by playing back an audio signal on an audio playback device 105(box 600). This audio playback device 105 may be a mobile phone 200 orany other type of device capable of playing audio content 125. The audiosignal typically contains audio content 125 either stored on the audioplayback device 105 or obtained external to the audio playback device105.

During the playback of the audio signal an audio capture device 135captures sound (box 610). The audio capture device 135 may be containedon the audio playback device 105 or in communication with the audioplayback device 105. During audio playback an audio indicator is alsoplayed on the audio playback device 105 (box 620). This audio indicatormay be a special audio tone or a watermark. The audio indicator may beaudible to the human ear or inaudible to the human ear (such asfrequencies higher that the human ear can perceive).

In some embodiments the audio indicator is played back continuously. Inother embodiments the audio indicator is played back at various timesand only for a specific duration (box 630). This operation is shown asoptional by the dashed box. The audio capture device 135 listens for theaudio indicator during the playback of the audio signal (box 640). Thesound captured by the audio capture device 135 during the audio contentplayback is analyzed to determine whether the audio indicator ispresent. Based on this analysis the system 100 determines the activeaudio output (box 650).

If the system 100 determines that the audio indicator is present in theplayback of the audio signal (or the sound captured by the audio capturedevice 135) then the active audio output is a loudspeaker 220 (box 660).If the system 100 determines that the audio indicator is not present inthe playback of the audio signal (or the sound captured by the audiocapture device 135) then the active audio output is headphones 230 (box670).

Many other variations than those described herein will be apparent fromthis document. For example, depending on the embodiment, certain acts,events, or functions of any of the methods and algorithms describedherein can be performed in a different sequence, can be added, merged,or left out altogether (such that not all described acts or events arenecessary for the practice of the methods and algorithms). Moreover, incertain embodiments, acts or events can be performed concurrently, suchas through multi-threaded processing, interrupt processing, or multipleprocessors or processor cores or on other parallel architectures, ratherthan sequentially. In addition, different tasks or processes can beperformed by different machines and computing systems that can functiontogether.

The various illustrative logical blocks, modules, methods, and algorithmprocesses and sequences described in connection with the embodimentsdisclosed herein can be implemented as electronic hardware, computersoftware, or combinations of both. To clearly illustrate thisinterchangeability of hardware and software, various illustrativecomponents, blocks, modules, and process actions have been describedabove generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. The described functionality can be implemented in varying waysfor each particular application, but such implementation decisionsshould not be interpreted as causing a departure from the scope of thisdocument.

The various illustrative logical blocks and modules described inconnection with the embodiments disclosed herein can be implemented orperformed by a machine, such as a general purpose processor, aprocessing device, a computing device having one or more processingdevices, a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA) orother programmable logic device, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. A general purpose processor andprocessing device can be a microprocessor, but in the alternative, theprocessor can be a controller, microcontroller, or state machine,combinations of the same, or the like. A processor can also beimplemented as a combination of computing devices, such as a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

Embodiments of the active audio output detection system 100 and methoddescribed herein are operational within numerous types of generalpurpose or special purpose computing system environments orconfigurations. In general, a computing environment can include any typeof computer system, including, but not limited to, a computer systembased on one or more microprocessors, a mainframe computer, a digitalsignal processor, a portable computing device, a personal organizer, adevice controller, a computational engine within an appliance, a mobilephone, a desktop computer, a mobile computer, a tablet computer, asmartphone, and appliances with an embedded computer, to name a few.

Such computing devices can be typically be found in devices having atleast some minimum computational capability, including, but not limitedto, personal computers, server computers, hand-held computing devices,laptop or mobile computers, communications devices such as cell phonesand PDA's, multiprocessor systems, microprocessor-based systems, set topboxes, programmable consumer electronics, network PCs, minicomputers,mainframe computers, audio or video media players, and so forth. In someembodiments the computing devices will include one or more processors.Each processor may be a specialized microprocessor, such as a digitalsignal processor (DSP), a very long instruction word (VLIW), or othermicro-controller, or can be conventional central processing units (CPUs)having one or more processing cores, including specialized graphicsprocessing unit (GPU)-based cores in a multi-core CPU.

The process actions of a method, process, block, or algorithm describedin connection with the embodiments disclosed herein can be embodieddirectly in hardware, in software executed by a processor, or in anycombination of the two. The software can be contained incomputer-readable media that can be accessed by a computing device. Thecomputer-readable media includes both volatile and nonvolatile mediathat is either removable, non-removable, or some combination thereof.The computer-readable media is used to store information such ascomputer-readable or computer-executable instructions, data structures,program modules, or other data. By way of example, and not limitation,computer readable media may comprise computer storage media andcommunication media.

Computer storage media includes, but is not limited to, computer ormachine readable media or storage devices such as Bluray discs (BD),digital versatile discs (DVDs), compact discs (CDs), floppy disks, tapedrives, hard drives, optical drives, solid state memory devices, RAMmemory, ROM memory, EPROM memory, EEPROM memory, flash memory or othermemory technology, magnetic cassettes, magnetic tapes, magnetic diskstorage, or other magnetic storage devices, or any other device whichcan be used to store the desired information and which can be accessedby one or more computing devices.

Software can reside in the RAM memory, flash memory, ROM memory, EPROMmemory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM,or any other form of non-transitory computer-readable storage medium,media, or physical computer storage known in the art. An exemplarystorage medium can be coupled to the processor such that the processorcan read information from, and write information to, the storage medium.In the alternative, the storage medium can be integral to the processor.The processor and the storage medium can reside in an applicationspecific integrated circuit (ASIC). The ASIC can reside in a userterminal. Alternatively, the processor and the storage medium can resideas discrete components in a user terminal.

The phrase “non-transitory” as used in this document means “enduring orlong-lived”. The phrase “non-transitory computer-readable media”includes any and all computer-readable media, with the sole exception ofa transitory, propagating signal. This includes, by way of example andnot limitation, non-transitory computer-readable media such as registermemory, processor cache and random-access memory (RAM).

The phrase “audio signal” is a signal that is representative of aphysical sound. One way in which the audio signal is constructed bycapturing physical sound. The audio signal is played back on a playbackdevice to generate physical sound such that audio content can be heardby a listener. A playback device may be any device capable ofinterpreting and converting electronic signals to physical sound.

Retention of information such as computer-readable orcomputer-executable instructions, data structures, program modules, andso forth, can also be accomplished by using a variety of thecommunication media to encode one or more modulated data signals,electromagnetic waves (such as carrier waves), or other transportmechanisms or communications protocols, and includes any wired orwireless information delivery mechanism. In general, these communicationmedia refer to a signal that has one or more of its characteristics setor changed in such a manner as to encode information or instructions inthe signal. For example, communication media includes wired media suchas a wired network or direct-wired connection carrying one or moremodulated data signals, and wireless media such as acoustic, radiofrequency (RF), infrared, laser, and other wireless media fortransmitting, receiving, or both, one or more modulated data signals orelectromagnetic waves. Combinations of the any of the above should alsobe included within the scope of communication media.

Further, one or any combination of software, programs, computer programproducts that embody some or all of the various embodiments of theactive audio output detection system 100 and method described herein, orportions thereof, may be stored, received, transmitted, or read from anydesired combination of computer or machine readable media or storagedevices and communication media in the form of computer executableinstructions or other data structures.

Embodiments of the active audio output detection system 100 and methoddescribed herein may be further described in the general context ofcomputer-executable instructions, such as program modules, beingexecuted by a computing device. Generally, program modules includeroutines, programs, objects, components, data structures, and so forth,which perform particular tasks or implement particular abstract datatypes. The embodiments described herein may also be practiced indistributed computing environments where tasks are performed by one ormore remote processing devices, or within a cloud of one or moredevices, that are linked through one or more communications networks. Ina distributed computing environment, program modules may be located inboth local and remote computer storage media including media storagedevices. Still further, the aforementioned instructions may beimplemented, in part or in whole, as hardware logic circuits, which mayor may not include a processor.

Conditional language used herein, such as, among others, “can,” “might,”“may,” “e.g.,” and the like, unless specifically stated otherwise, orotherwise understood within the context as used, is generally intendedto convey that certain embodiments include, while other embodiments donot include, certain features, elements and/or states. Thus, suchconditional language is not generally intended to imply that features,elements and/or states are in any way required for one or moreembodiments or that one or more embodiments necessarily include logicfor deciding, with or without author input or prompting, whether thesefeatures, elements and/or states are included or are to be performed inany particular embodiment. The terms “comprising,” “including,”“having,” and the like are synonymous and are used inclusively, in anopen-ended fashion, and do not exclude additional elements, features,acts, operations, and so forth. Also, the term “or” is used in itsinclusive sense (and not in its exclusive sense) so that when used, forexample, to connect a list of elements, the term “or” means one, some,or all of the elements in the list.

While the above detailed description has shown, described, and pointedout novel features as applied to various embodiments, it will beunderstood that various omissions, substitutions, and changes in theform and details of the devices or algorithms illustrated can be madewithout departing from the scope of the disclosure. As will berecognized, certain embodiments of the inventions described herein canbe embodied within a form that does not provide all of the features andbenefits set forth herein, as some features can be used or practicedseparately from others.

Moreover, although the subject matter has been described in languagespecific to structural features and methodological acts, it is to beunderstood that the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

What is claimed is:
 1. A method for automatically detecting an activeaudio output of an audio playback device, comprising: playing back audiocontent on the audio playback device; capturing sound during audiocontent playback using an audio capture device in communication with theaudio playback device; analyzing whether the captured sound matches theaudio playing back on the audio playback device to generate an analysis;and determining the active audio output of the audio playback devicebased on the analysis.
 2. The method of claim 1, further comprisingdetermining that the active audio output of the audio playback device isa loudspeaker if the captured sound matches the audio playing back onthe audio playback device.
 3. The method of claim 1, further comprisingdetermining that the active audio output of the audio playback device isheadphones if the captured sound does not match the audio playing backon the audio playback device.
 4. The method of claim 1, furthercomprising modifying the audio content playback based on thedetermination of the active audio output.
 5. The method of claim 1,wherein the audio capture device is a microphone on the audio playbackdevice.
 6. The method of claim 1, wherein the audio capture device is amicrophone in communication with the audio playback device.
 7. Themethod of claim 1, further comprising determining the active audiooutput of the audio playback device based on the analysis without theuse of special audio tones or audio watermarks.
 8. The method of claim1, further comprising sending a signal from the audio playback device toanother device in communication with the audio playback deviceindicating the active audio output of the audio playback device.
 9. Amethod for reducing analysis complexity of determining an active audiooutput of a device; comprising: playing an audio indicator through thedevice; listening for the audio indicator using a microphone; anddetermining the active audio output of the device based on listening forthe audio indicator.
 10. The method of claim 9, wherein the audioindicator is outside a human audible frequency range.
 11. The method ofclaim 9, further comprising: playing audio content other than the audioindicator simultaneously with the audio indicator; and ignoring theaudio content other than the audio indicator.
 12. The method of claim 9,further comprising playing the audio indicator at various times and fora specified duration and not continuously.
 13. A method for determininga type of audio reproduction device in communication with an audioplayback device, comprising: playing back audio content on the audioplayback device over the audio reproduction device; listening for theaudio content during playback using an audio capture device to determinewhether the audio content being played back is present; determining thatthe type of audio reproduction device is a loudspeaker if the audiocontent is present; and determining that the type of audio reproductiondevice is headphones if the audio content is not present.
 14. The methodof claim 13, further comprising applying an audio processing techniquedesigned for loudspeakers if the determination is that the type of audioreproduction device is a loudspeaker.
 15. The method of claim 13,further comprising applying an audio processing technique designed forheadphones if the if the determination is that the type of audioreproduction device is headphones.
 16. A system for automaticallydetermining a type of audio reproduction device connected to a mobilephone, comprising: audio content that is played back on the mobile phonethrough the audio reproduction device; an audio capture device thatcaptures sound while the audio content is being played back; an analysisprocessor that performs an analysis as to whether the audio content ispresent in the captured sound; and a selection processor that determinesthe type of audio reproduction device based on the analysis.
 17. Thesystem of claim 16, further comprising an audio processing technique forloudspeakers that is applied to the audio content if the selectionprocessor determines that the type of audio reproduction device is aloudspeaker.
 18. The system of claim 16, further comprising an audioprocessing technique for headphones that is applied to the audio contentif the selection processor determines that the type of audioreproduction device is headphones.